Mark J. Kirwan Paper and Paperboard Packaging Technology
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7 Fibre drums
Fibrestar Drums Ltd
7.1 Introduction
A fibre drum is a cylindrical container with a sidewall made of paper or paperboard
having ends and components made of similar or other materials such as metal, plastics,
plywood or composite materials. The sidewall of drums used for industrial appli-
cations is made up of several layers of paper laminated together by convolute winding.
Fibre drums are used globally and offer a strong, cost-effective means for the
packaging of solid, granular, powder, paste, semi-liquid and liquid products. They
are widely used by the chemical, pharmaceutical and food industries as well as for
special applications in other industries, such as the packing and dispensing of wire,
cable and metal foil, adhesives, rolled sheet materials, dyestuffs and colourants.
A US survey indicated that fibre drums comprised 30% of the industrial containers
(drums) market (Hanlon et al., 1998).
A comprehensive range of open-top fibre drums is produced in sizes from 10l
up to 270l capacity (2–60 imp. gal) and in a wide range of designs with respect to
diameter, height, cross section, type of closure and lid/base construction (Fig. 7.1).
Fibre drums are strong and protect their contents during transportation and
under compression whilst in storage. In general terms, they are capable of holding
up to 250kg (550lb) of dry or semi-liquid product, but with today’s Health and
Safety legislation, typical pack weights are 25 kg (55 lb) or 50 kg (110 lb).
Fibre drums were originally introduced as an alternative to the metal drum and
therefore had a circular cross section. In recent years, drums with a square cross
section with rounded corners have become available (Fig. 7.2).
Figure 7.1 Various designs of fibre drum.
Paper and Paperboard Packaging Technology
Edited by Mark J. Kirwan
Copyright © 2005 by Blackwell Publishing Ltd
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PAPER AND PAPERBOARD PACKAGING TECHNOLOGY
The square cross-section drums enable customers to make use of the space saving
attributes when such a pack is palletised for storage and distribution.
Fibre drums are made primarily, and in some designs exclusively, from fibrous
materials, namely paper and paperboard, as in Figure 7.3. Figure 7.5 shows a fibre
drum with a strengthened fibre top rim or chimb. This all fibre drum has a metal
closure band and options with respect to a plastic lid and base collar. Several
designs, however, incorporate metal components, plastic liners and coatings to
meet specific application needs.
One of the most important characteristics of the fibre drum is that manufacturers
are able to supply users with a bespoke, fully customised drum, to match their
packaging requirements exactly. Fibre drums are therefore not over specified and
hence follow the European Packaging Waste Directive for optimised packaging.
They are lighter than metal drums and, additionally, fibre drums are easily recovered
and their component parts recycled.
7.2 Raw material
The sidewalls are constructed using virgin unbleached kraft or a recycled paper
alternative, for example coreboard. A typical grammage would be 280g/m
2
. The strength
of the drum is strongly influenced by the type of paper and the number of plies
Figure 7.2 Square-round all-fibre drum with rounded corners.
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Figure 7.3 All-fibre drum with circular cross section and slip on lid.
Figure 7.4 Drum with fibre body, steel chimb on bottom, slip on lid.
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wrapped around the mandrel. End boards used in the base construction typically start
at 1275gsm and can be as high as 1800gsm.
Laminates based on these materials with, for example, aluminium foil, poly-
ethylene or other materials are used for additional functional properties, such as
moisture barrier. The additional barrier material may be ‘sandwiched’ within the
sidewall construction.
7.3 Production
7.3.1 Sidewall
The usual method for constructing the sidewall is by convolute or straight winding
of paper around a mandrel, or forming tool, from a reel, i.e. continuous length.
Adhesive is applied to the paper by an applicator roll rotating in an adhesive tray
prior to wrapping around the mandrel. A number of plies are built up on the mandrel,
for example 6 plies. The finished cylinder is then removed from the mandrel.
In this convolute winding, the diameter of the cylinder is the same as the diameter
Figure 7.5 All-fibre drum with fibre bead.
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of the mandrel on which it was wound and its length is the same as the width of the
paper from which it was wound.
After removal from the mandrel, the cylinder is left to stand for from 1 to 8
hours to allow the adhesive to dry. It is then cut to the required drum length, any
waste generated being recovered for recycling.
Winding on to the mandrel in this way means that the cross direction of the
paper becomes parallel to the axis of the newly wound cylinder with the machine
direction running around the circumference. This is an advantage as far as the strength
of the drum is concerned. There will be enough plies of paper to give the required
vertical stacking strength, and the body of the drum will have a greater resistance
to sideways impacts.
Paper laminates with additional functional properties are applied to the cylinder
in sheet form. Depending on the required position of the barrier material in the
drum construction, the material may either be wrapped around the mandrel prior to
or after the winding of the sidewall.
It should be noted that there are other methods of winding paper around a mandrel,
but they do not have the strength required for industrial drums. The use of these
methods, such as spiral and single-wall winding, is confined to the manufacture of
small retail size drums, decorative drums and hat boxes.
The industry standard, and most commonly used, adhesive is sodium silicate.
This adhesive is cost effective and efficient in the winding process, and contributes
to the strength of the drum.
For drums requiring moisture proof capability, polyvinyl acetate (PVA) is used.
There is also some use of polyvinyl alcohol and dextrine. The main requirements
for the adhesive are good wet tack and a quick setting speed. It is important to use
an adhesive with a high solids content to ensure that the amount of water added, as
a consequence of using the adhesive, is kept to a minimum.
7.3.2 Drum base
The fibreboard discs are die-cut from larger parent sheets; this is usually
done in-house for low-volume requirements, and higher-volume require-
ments are bought in from specialist suppliers. For the all-fibre drum, the
base is fixed in place by sandwiching it between a turned over flange and an
outer thinner disc.
A galvanised steel chimb on the bottom rim of the sidewall may be used to
apply a plastic (PE) or steel base by crimping. This will make it easier for one
person to move the drum by rolling it along on the base rim.
Caulking is used to seal the chimb ‘joint’, hence producing a liquid-carrying
capability if required. A typical caulking compound is a moisture-curing poly-
urethane, which is applied as an extruded bead into the joint before it is
crimped.
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The chimb adds strength and enables the drum to meet the United Nations
(UN) performance standards. The incorporation of a chimb to the edges of both
the top and bottom ends is a global standard produced by all manufacturers in one
form or another.
7.3.3 Lid
Fibre drums are known as ‘open’ top drums. This means that they have a lid which
matches the diameter of the drum. The lid can be made from wood, plastic, steel or
fibreboard. The lid is held in place with a metal band, normally steel, Figure 7.6.
(Readers should note that there is another type of drum, having a different design,
known as a ‘tight head’ drum where the top is permanently fixed to the body.
These drums are made only from plastic or steel. Tight-head drums are used to
carry liquid or semi-liquid products, with two 2-in. diameter apertures in the top
which are closed by bungs.)
Lid
Closure Band
Chimb
Chimb
Base
Side wall
Available in a choice of diameters
Volume range 27–268 l
Drum height 195–1000 mm
Figure 7.6 Fibre/steel fibre drum with fibre body, steel chimb top and bottom, lid and closure band.
FIBRE DRUMS
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Depending on the global manufacturing location, there is a preference for the
lid material. In the UK, the most popular choice is plastic, both HDPE and LDPE.
Steel lids are used in high-performance specifications. Within the USA, choice of
the lid material is split approximately, evenly between plastic and fibreboard lids.
Steel is used where required. In mainland Europe, a wider variety of lid is used,
including plywood, steel, fibreboard and plastic.
Where a plastic lid is used, as in Figure 7.6, a 2
″
aperture bung can be incorp-
orated which can take a bung closure. This is used for filling, using a lance or pipe,
and dispensing liquid and semi-liquid products, such as PVA adhesives. An option
for easily dispensing the product with the drum on its side is to fit a large tap in the
bung housing.
Steel lids can be either varnished, galvanised or hot-dip galvanised for corrosion/
weather protection.
In order to assist the stacking of drums, and the stability of a stack of drums, it
is usual for the lids to be designed in such a way that they locate within the base
chimbs of the drums on the next layer. For drum specifications that require an air-tight
seal, a gasket is incorporated into the plastic or steel lid. Gasket material varies
between manufacturers, but the most common is a polyurethane foam gasket
flowed into the lid, or a rubber gasket ring bonded to the lid.
The choice of the lid material comes down to cost and performance requirements,
all the materials quoted being accepted around the world.
There are several ways of securing the lid to a drum:
•
For the design of drum shown in Figure 7.6, with a metal chimb at both
ends, for example Fibrestar ‘Leverpak’, the lid is secured in place by a metal
closure band or closure ring. The ring is normally made of steel and galvan-
ised for anti-corrosion protection. The locking-handle design varies around
the world. There are two basic designs: one incorporates a locking latch,
while the other incorporates a one-piece handle with the provision for a
security seal.
•
The majority of closure-band designs allow for the use of a tamper evident
security seal. There are many designs of standard industry seals, but one of
the most popular is known as the ‘fir tree’ or ‘Christmas tree’ seal.
•
For drum styles that have slip on lids, such as those shown in Figures 7.3
and 7.4, the end-user would usually tape it in place with wide self-adhesive tape.
•
The square cross-section all-fibre drum, Figure 7.2, has a provision for securing
the lid by means of plastic tie straps, which are inserted through a set of holes
in its corners.
7.4 Performance
Fibre drums are used for the carriage of dry powders, granules, pastes and semi-
liquid products and other materials. As already noted, the main industrial sectors
that use fibre drums are the chemical, pharmaceutical and foodstuff sectors.
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Fibre drums which conform with UN Packaging Group I, II or III Standards are
often used to transport hazardous products in dry/solid form. Fibre drums cannot
be used to transport or pack hazardous liquids. Tests are clearly laid down in the
UN Orange Book, which defines the drum specifications that can be used for
specific products.
Every country has its own national testing authority to undertake and/or validate
testing carried out in other testing facilities. This testing may be carried out in
facilities owned by drum manufacturers, provided such facilities have been approved
by the national testing authority. The national testing authority issues certificates
when test data is submitted to it in the required manner.
The tests themselves are clearly laid down by the UN. They incorporate a variety
of drop tests at different angles of drum impact, along with a stacking test, at
23 °C, 50% RH.
Stacking performance, due to the very nature of the fibre drum being a bespoke
designed container for a specific, vertically stacked application, means that the stacking
performance or capability will vary as between the various sizes, design and specifica-
tion of drum. As a guideline, a drum for packing 25kg (55lb) of product could be
designed to allow a maximum of 10-high stacking. Whereas a drum for packing
200kg (440lb) of product could be designed to allow a maximum of 3 high stacking.
Handling of fibre drums can be undertaken manually, but above 50kg (110 lb)
handling would typically be by means of vacuum lifting, mechanical drum-handling
equipment or forklift truck. Fibre drums can be handled by all these methods.
When fibre drums are used to pack moisture sensitive and flavour or aroma
sensitive, semi-liquid and liquid products, the interior of the drum is integrally
lined with a polyethylene-lined paper or a PE aluminium foil lined paper, thus
stopping the product from penetrating the fibre sidewall body. Such barrier lining
protects the product from losing moisture, flavour or aroma and prevents contam-
inating odours, flavours and aromas from affecting the product. The base joint is
also normally sealed with a caulking compound to prevent the liquid from leaking
through the joint, whilst the lid will include a gasket. When required for a liquid,
or semi-liquid product, a PE strip is heat sealed over the lap join on the inside of
the straight wound drum to ensure that the product is not absorbed by the otherwise
exposed (raw) edge of paper.
The use of an integral barrier material plus caulking allows drums to be used
without the need for a separate loose polythene liner where the product requires
that type of protection. Hot-molten products which solidify on cooling can be
packed in fibre drums which have silicone-coated paper as the inside liner of the
drum. Removal of the product is usually facilitated by cutting away the container
or by the use of special drum heating equipment.
Fibre drums which are required to be suitable for external storage – the exterior
surface of the sidewall body is likely to be exposed to the natural elements such as
rain, snow, frost and sun – will incorporate a weatherproof barrier or coating and
the lid will include a gasket for improved sealing. Fibre drums can be externally
varnished to provide moisture protection.
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The vast majority of fibre drum users, when packing, for example dry powders,
would use a separate plastic bag, usually polyethylene (PE), as the first level of
protection, Figure 7.7. Other higher specification coextrusions can also be used.
The bags can be inserted by the drum manufacturer. Bags can be fixed to the drum
base by heat sealing or with the use of a semi-permanent adhesive. This has sev-
eral advantages:
•
drums are ready to use when delivered to the end-user
•
end-user stock control and labour costs are lower
•
fixed bags speed up product discharge and prevent them, accidentally,
entering reactors and blenders
•
semi-permanently fixed bags are easily removed from the drum for reuse or
disposal.
If the highest barrier/moisture protection is required the drum would, depending
on the product, have a PE/aluminium foil lining or PE barrier built into the drum
sidewall, with a gasket seal added to the lid.
Fibre drums incorporating a bag with high barrier properties can be used for
aseptic, hot-fill packaging.
Fibre drums with recessed ends provide edge protection for reels of mater-
ials such as plastic film, aluminium foil and rolls of plastic sheeting and floor
coverings.
The wire-manufacturing industry uses a special design of fibre drum, which
incorporates an additional core secured into the base of the drum. There is a choice
of design. The core may be glued around a stapled-in locating disc, or it may be
glued into a hole formed by a ‘donut’ shaped base disc. Wire and cable products
are packed in the void between the inner core and the drum sidewall. Drums such as
these are used for long duration feeding of welding wire and other similar products,
thereby reducing the number of changeovers for manufacturers.
Figure 7.7 Inserted plastic bag.
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Cleanliness of the drums is an important feature and some customers, such as
those in the pharmaceutical/fine chemicals sector, require packs that have passed
through an air-wash system which removes fibrous debris from the inside of the
drum, as shown in Figure 7.8.
7.5 Decoration, stacking and handling
The standard brown/beige fibre drum can be roller coated either with a colour or
clear varnish, to provide a wipe-clean surface, corporate image (‘house’ or brand
colour) and, as noted above, a moisture-resistant surface. Water-based inks and
varnishes also can be used.
The body can also be silk screen printed, normally up to a maximum of three
colours. Printing can include product/user instructions, safety and hazard-warning
data. If the design required and volume required are cost effective, a pre-printed
outer wrap can be applied when the cylinder is manufactured, hence allowing
multi-colour complex designs to be added to the fibre drum.
Labels can also be applied to the drum body if required, and these labels,
including the adhesive, are usually application specific, for example for internal or
external storage. Where the label is to be applied by the filler the fibre drum manu-
facturer can print a label location guide on the drum surface to enable the filler to
position the labels correctly.
Pigmented plastic lids are available to complement drum sidewall decoration.
Figure 7.8 Drums in air-cleaning facility.